Topography and SoilS 1010 - BHP...proposed expansion are discussed in Chapter 12, Groundwater,...

Olympic Dam Expansion Draft Environmental Impact Statement 2009 289

10Topography and SoilS 10

10.1 inTroducTionThe EIS Study Area has a topography of generally low relief. The

area around Olympic Dam is dominated by a landform of low

undulating dunes, swales and clay pans. To the north the land is

generally flat to undulating and comprised mainly of gibber

plains and rises, outwash plains and dunefields. To the south

are various tablelands, dunefields and alluvial plains, occasionally

separated by plateaus and steep escarpments. Surface materials

range from stones through sands, silts and clays.

The soil types of the Olympic Dam area and the study corridor

to Port Augusta were detailed in both the 1982 and 1997

Olympic Dam EIS (Kinhill-Stearns Roger 1982; Kinhill 1997). This

chapter describes the topography and the physical and chemical

properties of the soil types within the EIS Study Area. It also

explains how soil disturbance during the construction and

operation phases of the proposed expansion may affect the

surrounding environment. Where necessary, management

measures that would reduce potential impacts are identified.

The assessment also addresses the potential for soil

contamination from accidental spills. Potential health and

safety risks associated with soil contamination are discussed in

Chapter 22, Health and Safety.

Descriptions of the geology and geochemical properties of

sub-surface materials relevant to the study area of the

proposed expansion are discussed in Chapter 12, Groundwater,

because of their direct influence on groundwater quality.

10.2 aSSeSSmenT meThodS

10.2.1 Topography

Descriptions of topographical conditions across the project

components are based on the data sources shown in Table 10.1

and presented in Figures 10.1 and 10.2.

An analysis of the terrain of the Olympic Dam Special Mining

Lease (SML) was undertaken as part of the 1982 EIS at a

1:40,000 scale. The terrain pattern and terrain unit

classification system was based on a combination of the

underlying geology, landform type, physiographic description

and soil type.

10.2.2 SoilS

Soil descriptions

Houghton Environmental Management Pty Ltd (gas pipeline

corridor options) and URS Australia Pty Ltd (southern

infrastructure corridor) (see Appendix I1 for details) conducted

desktop and field survey investigations of soils within the

EIS Study Area. These studies also referenced the soil surveys

and descriptions undertaken as part of the two previous EIS

documents for the existing Olympic Dam operation (Kinhill-

Stearns Roger 1982; Kinhill 1997). The publications reviewed as

part of the desktop investigation are cited, where relevant,

within this chapter and listed in full in Appendix I1.

Field investigations were undertaken to confirm the soil types

of the EIS Study Area and soil samples were collected to assess

their physical and chemical properties in the laboratory.

Samples were obtained for the gas pipeline corridor options

from 22 test holes along the three alignment options (see

Figure 10.3). Samples were obtained for the southern

infrastructure corridor from 91 test pits, with at least three

representative samples collected from each soil type (see

Figure 10.4). The depth of the test pits varied from 1.5 to 3.5 m,

consistent with likely depths of excavation works associated

with proposed infrastructure.

Soil profiles were logged and described at each site in

accordance with the Australian Soil and Land Survey Field

Handbook (McDonald et al. 1990) and soil types were described

according to the unified soil classification system (USCS).

Olympic Dam Expansion Draft Environmental Impact Statement 2009290

IslandLagoon

Lake Torrens

(30 m AHD)

PernattyLagoon

LakeWindabout

Lake MacFarlane

LakeDutton

Pimba

Whyalla

Andamooka

Roxby Downs

Port Augusta

Woomera

Point Lowly

OLYMPICDAM

Flinders Ranges(~500 to 800 m AHD)

Corraberra Hill(309 m AHD)

Moomba(~50 m AHD)

Lake Eyre(-15 m AHD)

Lake Blanche

Lake Frome

Marree(48 m AHD)

Lyndhurst(124 m AHD)

Port Pirie

Baxter Range(~300 m AHD)

Andamooka Ranges(~120 m AHD)

Arcoona Ranges(~257 m AHD)

44

9

5

52

6326 422641

41 422734 38

2816 2614

23

25 2634

3015 334822

75 262142

7929 2433 7230 35

2319 27

2721 6212 18 71

16 2915

1751

747192

69288724

3424

87

76

9897

97

9587

95

70

83

90

59

5145

74 2444

816144

701925

3535

25

107

119112 136

112165

128110

109109

116

118

125

112106

105125110

109

109114

113

152

224174

232

130

130156

275278

245292 266

289249

116

Spot elevations (m AHD)

Elevation (m AHD)

High : 1,000

Low : -20

Landing facility

Desalination plant

Gas pipeline alignment options

Water pipeline alignment

Adjacent Olympic Dam - SA Governmentwater pipeline alignments

Transmission line alignments

Rail alignment

Access corridor

Existing Olympic Dam Special Mining Lease

Existing Roxby Downs Municipality

EIS Study Area

Proposeddesalination plant

Santosfacilities

Port BonythonJetty

See inset

InsetPoint Lowly

5 m AHD

25 m AHD

0 10 20 30 40 50km

Moomba

Adelaide

Port Pirie

Roxby Downs

Port Augusta

Whyalla

Figure 10.1 Topography of the project area


10

Table 10.1 Topographic data sources

location Scale Source date

South Australia 1:250,000 (50 m interval contours)

Geoscience Australia 2006

Water and power infrastructure corridors

North of 32° latitude: 1:250,000 (50 m interval contours)


South of 32° latitude: 1:50,000 (10 m interval contours)

Department for Environment and Heritage

2005

Rail line corridor 1:250,000 (50 m interval contours)


Gas pipeline corridor options 1:250,000 (50 m interval contours)


SML and Roxby Downs 1:12,500 (2.5 m interval contours)

Fugro Spatial Solutions 2006

Roxby Downs 1:5,000 (1 m interval contours)

Fugro Spatial Solutions 2006

Port Augusta 1:25,000 (5 m interval contours) plus spot heights


2006

Point Lowly 1:10,000 (2 m interval contours) plus spot heights


2004

Port Adelaide 1:10,000 (5 m interval contours) plus spot heights


2006

Water pipeline alignmentAdjacent Olympic Dam - SA Governmentwater pipeline alignmentsTransmission line alignmentsAccess corridor

Flinders Ranges(~500 to 800 m AHD)

Corraberra Hill(309 m AHD)

Simmens Hill(278 m AHD)

UpperSpencer Gulf

Point Lowly

Whyalla

Port Augusta

Figure 10.2 Topography from Point Lowly to Port Augusta

Laboratory testing of collected samples was undertaken at

NATA accredited laboratories to quantify the physical and

chemical properties of the material; these influence erosion

potential and soil stability. Chemical analysis was also

undertaken to establish baseline data for future comparison.

The parameters tested included field pH and electrical

conductivity, and concentrations of arsenic, cadmium,

chromium, copper, lead, nickel, zinc, mercury, uranium,

ammonia, nitrogen, phosphorus and organic matter.

Olym

pic Dam

Expansion Draft Environm

ental Impact Statem

ent 2009292

OLYMPICDAM

Marree

FinnissSprings

Murnpeowie

5

16

10

26

17

1

14

Lake Eyre North

Lake Torrens

Lake Eyre South

Lake Blanche

LakeGregory

Moomba

Andamooka

Roxby Downs

Lyndhurst

kp0

kp80

kp60

kp40

kp20

kp440

kp420

kp400

kp380

kp360

kp340

kp320

kp300

kp280

kp260kp240

kp220

kp560

kp540

kp520

kp500

kp480

kp460

kp440

kp420

kp400

kp380kp360

kp340

kp320

kp300

kp280

kp260kp240kp220

kp200

kp180

KP 160

kp140

kp120

kp100

9

5

16

23

12

6

18

16

21

17

7

6

13

20

1

3

26

16

10

81

24

26

14

16

16

Moomba

Whyalla

Adelaide

Port Pirie

Roxby Downs

Port Augusta

0 10 20 30 40 50km

Soil sample location

Kilometre point (kp)




EIS Study Area

Land systems

Arcoona - undulating tableland

Blanche - saltlake country

Collina - eroded and saline dunefield

Cooper - channels, lakes and swamps

Cooryaninna - channels, swamps and floodplain

Emu - sandstone ridges

Flint - steep rocky mesas

Hope - dunefields

Kalatinka - clay and loam flats

Kopi - crabhole flats and undulating plains

Mumpie - undulating gibber tableland

Oodnadatta - undulating gibber tableland

Roxby - dunefields and plains

Strzelecki - dunefields

Stuarts Creek - sandy and clay flats

Tingana - linear dunefields

Tirari - sandhills and flats

Wirringina - sandplains, dunes and sand

23

24

26

21

20

18

17

16

10

12

13

14

8

7

6

5

3

1

OLYMPICDAM Andamooka

Moomba

Gas pipeline alignment optionsOption 1


MoombaOption 2


MoombaOption 3

Figure 10.3 Land systems and soil sampling locations along the gas pipeline corridor options


10

OLYMPICDAM

Roxby Downs

LakeDutton

PernattyLagoon

IslandLagoon

Lake Torrens

Pimba

Andamooka

Woomera

Port Augusta

Point Lowly

1

Lake Torrens

Whyalla

BH1

BH2

BH3

BH4

BH5

BH7BH6

BH17

BH16

1

28

1

21

11

kp80

kp60

kp40

kp20

kp320

kp300

kp280

kp260

kp240

kp220

kp200

kp180

kp160

kp140

kp120

kp100

18

11

18

1

2227

1

19

25

18

11

21

1

4

25

18

27

2

4

15

Moomba

Whyalla

Adelaide

Port Pirie

Roxby

Augusta


Acid sulfate soil sample location


Landing facility

Desalination plant





Rail alignment

Access corridor

Existing Olympic DamSpecial Mining Lease


EIS Study Area

Land systems

Arcoona - undulating tableland

Bittali - undulating plains

Bowen - stony rises and plains

Hesso - sand sheets and plains

Lookout - shale hills and plains

Roxby - dunefields and plains

Saltia - alluvial foot slopes and plains

Stuarts Creek - sandy and clay flats

Tent Hill - stony tablelands and plains

Torrens - salt lake shorelines

Yorkey - saline sandplains and dunes

Yudnapinna - undulating gilgai plains

0 10 20 30 40 50km

1

2

4

11

15

18

19

21

22

25

27

28

Downs

Port

Figure 10.4 Land Systems and soil sampling locations along the southern infrastructure corridor


The concentrations of metals and nutrients were compared with

the National Environment Protection (Assessment of Site

Contamination) Measure (NEPM) health and ecological based

investigation levels (NEPC 1999). The concentrations of uranium

were compared to the United States Environmental Protection

Agency health based investigation level (US EPA 2004), as no

such level is published for South Australia or Australia.

acid sulfate soils

ENSR Australia Pty Ltd (ENSR) undertook desktop and field

investigations that assessed the potential for acid sulfate soils

(ASS) within the EIS Study Area, and to investigate the potential

effects of exposing such soils by excavation and trenching in

these areas. A summary of the assessment is provided in this

chapter, with supporting information provided in Appendix I2.

The term actual acid sulfate soils (AASS) is used when soils

have already oxidised and developed elevated acidity. AASS

typically have a field pH of less than 4 and mobile acidity in the

form of ionic hydrogen, aluminium, iron or acid salts. The term

potential acid sulfate soils (PASS) is used to describe soils that

have significant potential to generate acid on oxidation, but

which have not yet been oxidised.

South Australian ASS risk maps (Merry et al. 2003) and

topographic data were reviewed to locate areas within the

EIS Study Area with the potential to support the formation of

ASS (typically coastal areas below 5 m AHD and inland salt

lakes).

Samples were collected and handled according to the

Queensland Acid Sulfate Soil Technical Manual: Soil

Management Guidelines (Dear et al. 2002) and Guidelines for

Sampling and Analysis of Lowland Acid Sulfate Soils in

Queensland 1998 (Ahern et al. 1998) because there were no

detailed South Australian guidelines at the time of sampling.

A guideline for acid sulfate soil materials was published in 2007

by the South Australian Environment Protection Authority

(EPA 2007). It adopts the action criteria published by Ahern and

others (1998) and used in this assessment.

Table 10.2 criteria to determine significance of disturbance

Type of material 1–1,000 tonnes disturbed >1,000 tonnes disturbed

Texture range (mcdonald et al. 1990)

approximate clay content (%)

oxidisable sulphur (%S)1

Total actual acidity

(molh+/t)1,2

oxidisable sulphur (%S)1

Total actual acidity

(molh+/t)1,2

Coarse texture – sands to loamy sands ≤5 0.03 18 0.03 18

Medium texture – sandy loams to light clays

5–40 0.06 36 0.03 18

Fine texture – medium to heavy clays and silty clays

≥40 0.1 62 0.03 18

1 Calculated on an oven dry basis.2 Moles of hydrogen ions per tonne of soil. A measure of soil acidity.

An auger was used in the field investigations to dig 14 holes

to a depth varying between 0.3 and 2.3 m in those areas

identified through the desktop assessment as having the

highest potential for ASS. The depth of some holes was limited

because hard material was intercepted that could not be

penetrated with the hand auger. Nine sites were located in

low-lying coastal areas near Port Augusta and Point Lowly, and

seven were located in inland salt lakes and playas (see

Figure 10.4 for locations). Descriptions and samples of soils

were collected from the test holes at intervals of 0.5 m

(maximum) or at changes in stratigraphy.

During the field inspections, potential indicators of acid sulfate

soils were recorded if present. These include the presence of

acid tolerant plants, dieback and iron staining. Sediments

within the auger samples were reviewed for the presence of

jarosite, colour, texture, odour and neutralisation capacity

(e.g. shell content).

Fifty-eight samples were collected and screened for AASS using

the field pH in water (pHf) test, and screened for PASS using the

field peroxide pH test (pHfox) (see Appendix I2 for details).

A range of factors influences the magnitude and duration of

effects that may arise from the oxidation and leaching of PASS.

When interpreting the results of soil analyses the most

important of these are the permeability of the soil and the

quantity of acid that would be produced on oxidation.

The permeability of a soil is strongly influenced by its texture

and clay content, while the potential to produce acid is best

quantified by laboratory analysis to determine percentage of

oxidisable sulphur. Based on the field observations and the field

screening tests, 18 soil samples were selected for laboratory

analysis for total actual acidity (TAA), chromium reducible

sulphur and total sulphur (see Appendix I2 for details).

The combination of these factors defines the levels above which

the acid generating potential of a soil is considered to be

significant, and treatment is required if the soils are disturbed

(adapted from Dear et al. 2002). The criteria are shown in

Table 10.2.


10

10.2.3 impacT and riSk aSSeSSmenT

The assessment of impacts and risks for the proposed

expansion has been undertaken as two separate, but related,

processes (see Section 1.6.2 of Chapter 1, Introduction, and

Figure 1.11).

Impacts and benefits are the consequence of a known event.

They are described in this chapter and categorised as high,

moderate, low or negligible in accordance with the criteria

presented in Table 1.3 (Chapter 1, Introduction). A risk

assessment describes and categorises the likelihood and

consequence of an unplanned event. These are presented in

Chapter 26, Hazard and Risk.

10.3 exiSTing environmenT

10.3.1 Topography

Figure 10.1 shows topography and spot heights, illustrating the

generally flat terrain of the EIS Study Area. Dunes trending

east –west and up to around 8 m in height, swales and clay pans

(see Plate 10.1) dominate the Olympic Dam landscape. The

elevation is about 100 m AHD.

The gas pipeline corridor options between Moomba and

Olympic Dam vary between extensive dunefields, parallel dunes

with swales and clay pans, alluvial outwash plains and gibber

plains and rises (see Plate 10.2). The EIS Study Area from Pimba

to Port Augusta supports sand sheets and clay plains with low

topographic relief (see Plate 10.3). Between Port Augusta and

Point Lowly, the southern infrastructure corridor follows the

alluvial flood plains that separate the plateaus and steep

escarpments of the Tent Hill Formation (see Figures 10.2 and

10.4, and Plate 10.4). The highest point in the EIS Study Area,

Corraberra Hill (309 m AHD), is located approximately 55 km

north of Whyalla (see Figure 10.1).

The East Arm of the Port of Darwin lies within the Darwin

Harbour catchment. The topography of the catchment ranges

from flat intertidal and estuarine (marine) plains of negligible

slope, through to undulating hills and plateaus. Elevations

within the catchment range from sea level at the coastal

margins to around 140 m AHD in the southern foothills (Haig

and Townsend 2003). The proposed BHP Billiton facilities would

be located on flat, reclaimed land.

10.3.2 land SySTemS

The Department of Primary Industries and Resources SA (PIRSA)

has mapped South Australia’s land systems. This method

integrates several environmental features, so that each land

system combines areas of similar climate, geology, landform,

soil type and indigenous vegetation. The land systems within

the EIS Study Area are summarised in Table 10.3 and illustrated

in Figures 10.3 and 10.4.

Plate 10.4 Alluvial plains separating plateaus and steep escarpments

Plate 10.3 Low topographic relief between Pimba and Port Augusta

Plate 10.2 Landscape between Moomba and Olympic Dam showing parallel dunes and interdunal clay pans

Plate 10.1 Olympic Dam landscape showing the east-west trending dunes, swales and clay pans


Table 10.3 land systems of the eiS Study area

land system location (kilometre point (kp))

description approximate coverage

(% of eiS Study area)

gas pipeline corridor options (see Figure 10.3)

Arcoona 28–1 (28–1)1

Arcoona tablelands. Contains areas of undulating tablelands with bladder saltbush, neverfail, plover daisy and glasswort; escarpments of bladder saltbush, glasswort and woolly bluebush; swamps of blackbush, nitre goosefoot, cottonbush or canegrass and watercourses of dead finish

1.5 (1)1

Blanche 298–306 Salt lake country often with pale dunes on lake margins. Lake margins of bladder saltbush and samphire; Cobbler Desert with nitre bush, samphire, native myrtle and canegrass

2.5 (<1)

Collina 307–319 (400–482)

Highly eroded and saline dunefield of truncated parabolic dunes adjacent and north of the Lakes Callabonna/Blanche/Gregory complex; predominantly nitre bush dunes with broad saline flats and small plains and many small saline depressions

3 (15.5)

Cooper 420–448 (491–562)

Field of parallel dunes and extensive system of interconnected clay pans periodically flooded by Cooper Creek. Mixed cover of chenopod shrubland, tall shrubland with grass and forb understorey, hummock grassland, grassland and fringing woodland (Laut et al. 1977)

7 (11.5)

Cooryaninna 259–297 (262–275)

Channels, swamps and extensive crabhole floodplain of Cooryaninna Creek. Channels with coolibah, river cooba, Broughton willow and lignum; swamps with Queensland bluebush, canegrass and lignum; alluvial plains with Mitchell grass, common nardoo and annual grasses

8 (2.5)

Emu 30–35 Sandstone ridges of Billa Kalina. Ridges of mulga over emu bushes, cassias and grasses; slopes of bladder saltbush and grey glasswort with Mitchell grass and neverfail; shrubland plains of Oodnadatta saltbush with bladder saltbush, cottonbush and grasses

1 (0)

Flint 276–288 (292–300)

Steep rocky mesas of the Flint Hills, low hills and plains with dense silcrete gibber. Mesas with rock fuchsia bush, bladder saltbush and Mitchell grass; low hills and plains with bladder saltbush, cotton bush, tangled poverty bush, satiny bluebush and Mitchell grass

<1 (4)

Hope 320–419 Dunefield with north-south linear dunes between Cooper and Strzelecki creeks. Lacks any form of drainage systems but susceptible to flooding of eastern and western margins from high flows of the Cooper Creek

22.5 (<1)

Kalatinka 143–216 (143–216)

Clay and loam flats with Mitchell grass, neverfail, bladder saltbush and cottonbush and patches of prickly wattle and canegrass; low dunes with sandhill canegrass, nitre bush and sandhill wattle

13.5 (12.5)

Kopi (244–256) Relatively small areas of grey, gypsiferous crabhole flats and undulating plains with sparse cover of tangled poverty bush, flat topped saltbush and soft horns; shallow creeks with bushy groundsel, thorny saltbush and samphire

0 (1.5)

Mumpie 238–258 (227–244) (257–261) (289–291) (301–399)

Undulating gibber tableland country. Tableland with gilgais supporting barley and curly Mitchell grass, cottonbush, samphire, bladder saltbush, neverfail and bindyis; mesas with scattered mulga and low bluebush; larger creeks with river red gum, coolibah, Broughton willow and river cooba; minor creeks with dead finish and plumbush

7 (22.5)

Oodnadatta 93–142 Undulating gibber tableland with gilgai depressions, mesa and plateau country north and east of Marree. Gilgais with Oodnadatta saltbush, bladder saltbush and scattered samphire over native millet; barley, Mitchell grass, Flinders grass and annual herbs; low hills and mesas with low bluebush, bladder saltbush, harlequin emu bush and blackbush; creeks with mulga and coolibah

13.5 (10.5)

Roxby 0–27 Extensive dunefield over a calcareous plain. Dunes of native pine and mulga woodland over hopbush, woolly butt and kerosene grass; swales of mulga woodland over sandhill wattle, hopbush and grasses; myall woodland plains over pearl bluebush and limestone copper burr; flats of saltbush, star bush and sea-heath with swamps of tea-tree, canegrass or lignum

2.5 (2)

Strzelecki 217–237 (232–237)

Dunefields of Strzelecki Desert in the south-east of the district. Red dunes with whitewood, mulga, sandhill wattle, sandhill canegrass and lobed spinifex; sandy interdune flats with colony wattle, straggly corkbark over copper burrs and annual grasses; clay swales with Mitchell grass, neverfail and plate grass

4.5 (<1)


10

Table 10.3 land systems of the eiS Study area (cont’d)




gas pipeline corridor options (see Figure 10.3) (cont’d)

Stuarts Creek 31–92 Sandy and clay flats with widely spaced sand dunes found in the south and west of the district. Sandy plains with low bluebush and bladder saltbush; clay flats with tea tree, starbush, lignum and swamp canegrass; dunes with sandhill wattle, mulga, hopbush and sandhill canegrass

13.5 (10.5)

Tingana (483–490) Linear dunefield east of Strzelecki Creek of mostly hummock grassland and tall shrubland dunes, lacking any definite drainage. Dunes have a SSW-NNE trend. Cottonbush is the main bluebush species

0 (3)

Tirari North of pipeline alignment

Sandhills and flats of the Tirari Desert east of Lake Eyre, often known as Peachawarinna country. Includes channels and floodplains of the lower Cooper, Warburton and Kalakoopah creeks; dunes with sandhill canegrass, desert cynanchum and scattered sandhill wattle; variable flats with starbush, low bluebush and annual grasses; channels with coolibah and scattered nitre bush goosefoot swamps; salt lakes and clay pans with samphire

1 (<1)

Wirringina North and south of pipeline alignment

Red sandplains, dunes and sand accumulations on stony country. Salt lakes including Lake Harry; sandplains and dunes with needlewood, sandhill wattle, sandhill canegrass and starbush; salt lakes with samphire, tangled poverty bush and water weed; kopi lunettes with blackbush, bladder saltbush and Tates bindyi; creeks with coolibah, river cooba and old man saltbush

0 (1.5)

olympic dam and southern infrastructure corridor (see Figure 10.4)

Arcoona 175–195 215–230 235–245 250–275 290–295

Arcoona tablelands. Contains areas of undulating tablelands with bladder saltbush, neverfail, plover daisy and glasswort; escarpments of bladder saltbush, glasswort and woolly bluebush; swamps of blackbush, nitre goosefoot, cottonbush or canegrass and watercourses of dead finish

21

Bittali 5–10 20–30

Extensive undulating calcareous plains. Dominated by mallee woodland plains; myall, mallee and black oak woodland plains with cassia, wattles, sheepbush and daisy bush; and pediments of myall open woodland with mallee, pearl bluebush and spiny goosefoot

4.5

Bowen 125–130 170–175

Stony rises of bladder saltbush low shrubland with slender glasswort; plains and rises of pearl bluebush shrubland with brilliant hopbush, saltbush and spiny goosefoot; salt lakes fringed with samphire, bladder saltbush and star bush

3

Hesso 15–20 30

40–50 85–90

95–110 120–125 130–170

Extensive sand sheets with calcareous soils. Plains of myall, sugarwood woodland over pearl bluebush +/- bladder saltbush; and plains and rises of mulga and myall woodland with pin bush wattle, pearl bluebush and spiny fan flower

24

Lookout West of water pipe alignment

Silicified shale hills of the Stuart Range. Plains with low shrubland of bluebushes, saltbush, silvertails and spiny goosefoot; and rises with low shrubland of bluebushes, saltbush, spiny goosefoot and silvertails

<1

Roxby 110–120 195–210 230–235 245–250 275–290 295–335

Extensive dunefield over a calcareous plain. Dunes of native pine and mulga woodland over hopbush, woolly butt and kerosene grass; swales of mulga woodland over sandhill wattle, hopbush and grasses; and myall woodland plains over pearl bluebush and limestone copperburr; flats of saltbush, star bush and sea-heath with swamps of tea-tree, canegrass or lignum

26

Saltia South of Port Augusta Alluvial foot slopes and plains of stony red soils with bladder saltbush, low bluebush and scattered groves of black oak and prickly wattle

<1

Stuarts Creek Eastern boundary of SML

Sandy and clay flats with widely spaced sand dunes. Sandy plains with low bluebush and bladder saltbush; clay flats with tea tree, starbush, lignum and swamp canegrass; and dunes with sandhill wattle, mulga, hopbush and sandhill canegrass

<1

Tent Hill 0–5 30–40 50–70 75–85 90–95

Strongly dissected stony tablelands complex. Plains of bladder saltbush and glasswort shrubland with bluebush; footslopes and plains of low bluebush and bladder saltbush with some black oak; tablelands of bladder saltbush and slender glasswort; and watercourses of black oak and bladder saltbush

15


Table 10.3 land systems of the eiS Study area (cont’d)




olympic dam and southern infrastructure corridor (see Figure 10.4) (cont’d)

Torrens 210–215 Lake Torrens salina and shoreline. Salt crusted lake bed; flats and lake fringes of bladder saltbush, starbush or samphire; and lunettes of sandhill wattle and narrow-leaf hopbush over grasses

1.5

Yorkey 10–15 70–75

Saline sand plain. Dunes of mulga, myall or northern native pine over narrow-leaf hopbush and blackbush; swales of blackbush, slender glasswort and bladder saltbush; sandy flats of myall open woodland over blackbush, bladder and bitter saltbushes; and salt pans and fringing samphire flats

3

Yudnapinna West of water pipe alignment

Dissected, undulating plains. Gilgai plain with low shrubland of bladder saltbush, slender glasswort, bluebush and bush minuria, or bladder saltbush, low bluebush and blackbush. Low lying areas with low shrubland of blackbush, low bluebush, bladder saltbush, bush minuria and cottonbush

<1

1 Numbers in parentheses refer to the southern route of the gas pipeline corridor options, and numbers not in parentheses refer to the northern route of the gas pipeline corridor options and include the common section from Olympic Dam to near Lake Eyre.

10.3.3 SoilS

Soil descriptions

A description of soil units of the Olympic Dam region and the

infrastructure corridors is provided in Table 10.4. This table also

presents the corresponding land system, soil landscape and

environmental associations as described in the Atlas of Australian

Soils (CSIRO 1960 and 1968) and by Laut and others (1977).

Table 10.4 Soil unit descriptions and corresponding soil landscapes and land systems

Soil unit plate coverage general description general soil characteristics

Soil landscape1 land system2

description map unit

gas pipeline corridor options (see Figure 10.3)

Parallel dunes with inter-connected interdunal clay pans (Cooper drainage system)

10.3 From the Moomba gas fields area for approximately 30 km to the south-east or approximately 54 km to the south; (northern route, kp 420–560; southern route, kp 480–560)

Whitish sand dunes with broad interdunal clayey soils. Dunes are generally devoid of significant vegetation while clay pans have grass cover with some eucalypt vegetation

Sands: highly permeable siliceous sands, neutral

Clays of depressions: grey self-mulching cracking clays, alkaline

Uc1.21 (sands)

Ug5.24 (clays)

B51 Cooper (Cooper Creek)

Sand dunes with interdunal clay pans

10.5 Located along northern route from approximately 30 to 150 km south-east of Moomba; (northern route, kp 320–420)

Red and yellow sand dunes with massive earths in the depressions. Generally low vegetative cover

Sands: red or yellow siliceous sands, neutral

Clay pans: red massive earths, neutral

Uc1.23 (sands)

Gn2.12 (earths)

B51 Hope (Strzelecki Desert)

Eroded dunefields with intermittent saline flats

10.6 To the north-east of Lake Gregory and east of Lake Blanche; (northern route, kp 307–320; southern route, kp 400–480)

Whitish sand dunes with saline clay pans. Sparse vegetative cover

Sands: yellow siliceous sands, neutral

Clay pans: grey self-mulching cracking clay, alkaline

Uc1.23 (sands)

Ug5.24 (clays)

B51 Collina (Strzelecki Desert)

Salt lakes, deposits and associated margins

– Near Lake Gregory; (northern route, kp 295–305)

Salt crust overlying, clays, silts and quartz sands, or grey, plastic muds; some cracking clays. Generally devoid of vegetation

Calcareous, neutral to alkaline

Lakes and immediate environs

CC118 Blanche (Lake Frome)

The East Arm of the Port of Darwin is characterised by alluvial

and estuarine plains with extensive intertidal flats of saline

muds, clays and silts, foreshore areas of deposited sands and

shells, and a hinterland of shallow gravelly, sandy soils (NRETA

2007; Haig and Townsend 2003). East Arm (where the proposed

facilities would be located) was constructed through the

process of land reclamation and was formed from fill from

the surrounding area.


10

Plate 10.7 Sparse dunes of the Strzelecki land system

Plate 10.6 Eroded dunefields of the Collina land system

Plate 10.5 Sand dunes of the Hope land system




gas pipeline corridor options (see Figure 10.3)(cont’d)

Dunefields 10.7 Southern extremity of Tirari Desert; (northern route, kp 215–235; southern route, kp 220–225)

Red and yellow sand dunes. Sparse low vegetative cover

Red or yellow firm siliceous sands: neutral

Uc1.43, neutral

B43 Strzelecki (Kallakoopah)

Stony downs and gibber plains of the Blanchewater and Marree formations and associated outwash

10.8 Forms a large portion of the east-west arm of the southern route; (northern route, kp 200–260; southern route, kp 200–400; combined route, kp 90–200)

Undulating tablelands with extensive gibber surface rocks and little vegetation. Includes areas of clay and loam flats with increased vegetation

Crusty loamy soils with brown cracking clays

Stone surface matrix with expansive, slightly acid to alkaline clays in subsoils

Gibber surface rocks with grey/red clayey subsoils (Dr1.33)

Nb35/ Nb36

Mumpie, Flint, Kalatinka, Oodnadatta

Alluvial outwash plains

10.9 Channels and floodplains associated with Cooryaninna Creek and various creek systems associated with southern route; (northern route, kp 260–300; southern route, kp 260–275)

Alluvium and associated valley plains. Saltbush and some eucalypt adjacent to channels

Brown self-mulching cracking soils, neutral to alkaline

Ug5.2 or Ug5.3

BG1 Cooryaninna

Plate 10.9 Alluvial outwash plains associated with Cooryaninna Creek

Plate 10.8 Stony downs and gibber plains of the Blanchewater and Marree formations


Plate 10.10 Sand ridge of the Roxby land system

Table 10.4 Soil unit descriptions and corresponding soil landscapes and land systems (cont’d)

Soil unit Plate Coverage General description General soil characteristics

Soil landscape1 Land system2

Description Map unit

Gas pipeline corridor options (see Figure 10.3) (cont’d)

Shallow soils overlying Arcoona Quartzite and Bulldog Shale

– To the north of the Olympic Dam SML; (combined route, kp 25–30)

Thin fine-grained topsoil (~100 mm) with gibber surface rocks over heavy clays. Sparse vegetative cover

Highly expansive clays, low permeability when wet, slightly alkaline. Shrink-swell movements of the clayey soils have formed distinct mounds and depressions called gilgai

Crusty loamy soils with red clayey subsoils (Dr1)

Nb41 Arcoona


10.10 and 10.11

From Olympic Dam to approximately 90 km: (combined route, kp 0–90)

Red to reddish brown sand dunes with interdunal clayey soils with gibber surface rock and little vegetation

Clay pans generally have no surface rock and are devoid of vegetation

Sands: highly permeable, alkaline

Clays: expansive and low permeability when wet, cracking under low moisture conditions, alkaline, forms a hard surface skin

Sands (Uc1.23)

Brown calcareous earths (Gc)

DD1 Roxby and Stuarts Creek

Olympic Dam and southern infrastructure corridors (see Figure 10.4)


10.10 and 10.11

From Olympic Dam to approximately 15 km south of Purple Downs pastoral station; (kp 275–335, kp195–210)

Red to reddish brown sand dunes

Interdunal clayey soils with gibber surface rock and little vegetation

Clay pans generally have no surface rock and are devoid of vegetation

Sands: highly permeable, alkaline

Clays: expansive and low permeability when wet, cracking under low moisture conditions, alkaline, forms a hard surface skin


DD1 Roxby

Plate 10.12 Gibber plain of the Arcoona land system

Plate 10.11 Clay pan of the Roxby land system


10

Plate 10.14 Red sandy soils typical of the Hesso land system

Plate 10.13 Salt lake deposits

Plate 10.16 Alluvial sands of the Hesso land system





olympic dam and southern infrastructure corridors (see Figure 10.4) (cont’d)


10.12 South of Purple Downs to Lake Windabout; (kp 215–275)

Thin fine-grained topsoil (~100 mm) with gibber surface rocks over heavy clays

Highly expansive clays, low permeability when wet, slightly alkaline

Shrink-swell movements of the clayey soils have formed distinct mounds and depressions called gilgai


Nb41 Arcoona

Salt lakes and deposits

10.13 Found predominantly to the north of Port Augusta e.g. Lake Windabout, Ironstone Lagoon, Yorkey’s Crossing; (kp 210–215)

Salt crust overlying, clays, silts and quartz sands, or grey, plastic muds

Calcareous, neutral to alkaline

Lakes Lakes Torrens (north of Port Augusta)

Quaternary sandplains and sand dunes

10.14 Between Lake Windabout and approximately 20 km north of Port Augusta. Also present to the east of Woomera; (kp 85–170)

Red sandy soils with little or no fines and little or no surface rock

High permeability, low fertility, alkaline


DD1 Hesso

Shallow soils overlying Pernatty Grit

10.15 Generally found to the west of Pernatty Lagoon; (kp 180–195)

Red sandy topsoil up to 200 mm thick with gibber surface rock, over clay and clay loam

Highly permeable sands. Highly plastic and expansive clays, low permeability when wet, slightly acid to alkaline


Nb42 Arcoona

Quaternary soils of alluvial plains

10.16 Found between Port Augusta and Whyalla; (kp 15–20, kp 40–50)

Alluvial sands with some clays and silts up to 500 mm thick, over clay

Slightly acidic to alkaline


DD2 Hesso

Plate 10.15 Gibber surface rocks overlying soils in the Arcoona land system


erosion potential

Erosion potential is a measure of the degree to which soils are

susceptible to erosion. Classifications of low, medium, high or

very high are provided for each soil unit in the EIS Study Area

Table 10.5 Soil unit erosion potential

Soil unit (as per Table 10.4) erosion potential description

Sand dunes with interdunal clay pans Low to high Dunes highly susceptible to wind erosion. Bare clay pans subject to scalding from surface water

Dunefields Moderate to very high Dunefields inherently mobile and susceptible to wind erosion

Stony downs and gibber plains of the Blanchewater and Marree Formations and associated outwash

Low to high Surface gravel offers high degree of natural protection, however, exposure of dispersive subsoil in undulating terrain may have the potential for significant erosion

Quaternary alluvial plains Low (often high to very high at stream crossing)

Stream channels highly susceptible to stream bank erosion. Plains may be susceptible to sheet erosion


Low Removal of surface gravels may lead to some minor loss of surface soils

Salt lakes and deposits High to very high Susceptible to gullying and wind erosion when surface cover disturbed

Quaternary sandplains and sand dunes Medium to high Minor gullying associated with drainage features

Highly susceptible to wind erosion where surface cover disturbed

Shallow soils overlying Pernatty Grit Low Removal of surface gravels may lead to some minor loss of surface soils

Near coastal Quaternary soils Low to medium Removal of surface vegetation may lead to some minor loss of surface soils

Shallow soils overlying Tent Hill formation Low to medium Removal of surface vegetation may lead to some minor loss of surface soils. Higher risk on the stony slopes, where large gullies can form in areas of surface disturbance





olympic dam and southern infrastructure corridors (see Figure 10.4) (cont’d)

Near coastal Quaternary soils

10.17 Located in the coastal plains of the Port Augusta area and in the vicinity of False Bay near Point Lowly; (kp 10–15, kp 70–75)

Sandplains, salt pans and sand dunes

Interdunal swales with light clay loam soils

Generally saline, collapsing sands with low strength when wet, slightly alkaline

Sand soils of minimal development (Uc1)

Amorphous loamy soils (Um5)

A2

BB2

Yorkey

Shallow soils overlying Tent Hill formation

10.18 Found west and south of Port Augusta and near Point Lowly; (kp 0–5, kp 50–70)

Thin loamy topsoils (up to 200 mm) overlying clay and shallow sandstone

Alkaline Crusty loamy soils with red clayey subsoils (Dr1)

Na1 Tent Hill

1 As described in the Atlas of Australian Soils (CSIRO 1960 and 1968).2 Corresponding environmental associations, as described by Laut and others (1977), are provided in parentheses.

Plate 10.18 Shallow soils overlying the Tent Hill FormationPlate 10.17 Near coastal sand plains of the Yorkey land system

(see Table 10.5 and Figures 10.5 and 10.6). These classifications

have been based on laboratory tested Emerson Class, field tested

electrical conductivity and field observations of soil properties,

landform and erosion features (see Appendix I1 for details).

Olym

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ental Impact Statem

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10

OLYMPICDAM

Lyndhurst

Leigh Creek

Marree

Finniss Springs

Murnpeowie

Lake Eyre North

Lake Torrens

Lake Eyre South

Lake Blanche

LakeGregory

Moomba

Andamooka

Roxby Downs

William Creek

kp0

kp80

kp60

kp40

kp20

kp440

kp420

kp400

kp380

kp360

kp340

kp320

kp300

kp280

kp260kp240

kp220

kp560

kp540

kp520

kp500

kp480

kp460

kp440

kp420

kp400kp380kp360kp340

kp320kp300

kp280

kp260kp240kp220

kp200

kp180

kp160

kp140

kp120

kp100

Moomba

Whyalla

Adelaide

Port Pirie

Roxby Downs

Port Augusta

0 10 20 30 40 50km






EIS Study Area

Soil erosion potential(areas extrapolated from soil samples)

Low

Medium

High

Very high

Figure 10.5 Soil erosion potential along the gas pipeline corridor options


Whyalla

Woomera

PointLowly

Pimba

Andamooka

Roxby Downs

Port Augusta

OLYMPICDAM

LakeTorrens

IslandLagoon

LakeMacFarlane

LakeWindabout

PernattyLagoon

LakeDutton

kp60

kp40

kp20

kp320

kp300

kp280

kp260

kp220

kp200

kp180

kp160

kp140

kp120

kp100

kp80

kp240

Port Augusta

Whyalla

Port Pirie

Moomba

Adelaide

Roxby




EIS Study Area



Soil erosion potential(areas extrapolated from soil samples)

Low

Medium

High

Very high0 5 10 15 20 25

km

Downs

Figure 10.6 Soil erosion potential along the southern infrastructure corridor


10

Soil metals and nutrients

Soils sampled from the EIS Study Area reported concentrations

of metals typical of background levels (as presented in Berkman

1995). No concentrations were above NEPM health or

ecological-based guideline levels. Reported concentrations of

uranium were below the US EPA health-based soil investigation

level (see Appendix I1, Table I1.5 for full details).

Concentrations of soil nutrients and organic matter were also

low to very low. This is typical of soils in arid and semi-arid

environments that have a low natural fertility.

acid sulfate soils

Two types of acid sulfate soils (ASS) were identified:

Inland ASS – these ASS form in situations where there is a •

sulphate source, iron source and organic matter, all of which

occur in inland salt lakes. They occur in the near-surface

sediments (<10 mm) of salt lakes in the form of mono-

sulphides or ‘black ooze’. When disturbed, monosulphides

can react rapidly to form acid (i.e. within minutes to hours).

Coastal ASS – these ASS are generally associated with •

estuarine (marine) clays, but they also occur as sands and

gravels, and most often in areas below 5 m AHD. Sulphide

minerals are generally present in the form of iron

sulphide (pyrite). When exposed to oxygen these soils and

sediments become acid forming over longer periods (from

days to years), depending on the grain size.

The ASS risk mapping (Merry et al. 2003) suggests that the

coastal ASS may occur in some sections of the EIS Study Area

(see Figure 10.7). Section 10.5.2 presents the findings of the

field and laboratory investigation for inland and coastal ASS and

the potential impacts associated with the proposed expansion.

10.3.4 FoSSilS

As fossils are either composed of stone or embedded in stone,

and therefore fall within the definition of ‘minerals’, the Crown

owns fossils in South Australia, including fossils found on

pastoral or perpetual leasehold land and lands subject to native

title by virtue of the Mining Act 1971 (PIRSA 2004a).

Fossils of significance in South Australia are registered on the

Australian Heritage Places Inventory, the Australian Heritage

Database and the South Australian Heritage Register. The

significance of fossil assemblages is generally defined by

the abundance in which the fossil occurs. There are no areas

of registered fossils of significance within the EIS Study Area.

However, an official fossil reserve, Lake Callabonna, is located

within 1 km of the gas pipeline corridor options (see

Figure 10.8). The significance of the Lake Callabonna fossil

assemblage is the presence of fossils as articulated specimens,

including Australia’s largest Pleistocene aged marsupial, the

Diprotodon (Aussie Heritage 2008).

A second official fossil reserve, Lake Palankarinna, is located

approximately 30 km north of the gas pipeline corridor options

and is considered significant as it contains a diverse

stratigraphic sequence of Tertiary aged vertebrates (N Pledge,

SA Museum, pers. comm., 22 January 2008).

While not listed as being of significance, some fossils are known

to exist in the following lithologies (see Figures 10.8 and 10.9):

Cretaceous aged Bulldog Shale – grey, shaly mudstone •

known to contain fossil assemblages of macrofaunas

dominated by molluscs (Drexel et al. 1993)

Late Palaeocene aged Eyre Formation – silicified sandstone •

that may contain plant fossils or ‘silcrete floras’. These

fossils are particularly widespread south of Lake Eyre to

Lake Pernatty (N Pledge, SA Museum, pers. comm.,

22 January 2008).

10.4 deSign modiFicaTionS To proTecT environmenTal valueS

10.4.1 environmenTal valueS

Soils provide a natural foundation and supply of minerals and

water to plants and provide habitat for many organisms.

Disturbance to soils can affect structural integrity, change

chemical properties and alter the potential for re-establishment

of plants and animal habitat.

10.4.2 major elemenTS oF The projecT deSign

The key components of the project design that influence the

assessment of soils (see Chapter 5, Description of the Proposed

Expansion, for the full description of the project components)

are:

the extent of the proposed expansion and the corresponding •

areas requiring ground disturbance

the excavation of trenches to bury the gas supply pipeline, •

water supply pipeline and the intake and outfall pipes for

the desalination plant

the location of electricity transmission line towers (e.g. on •

topographically elevated sites)

excavation and construction of embankments for the railway •

line and access corridor.

Planning provides the greatest opportunity to reduce the

potential impacts on soils of the EIS Study Area. Where

possible, project infrastructure would be located to:

minimise disturbance to soils of high and very high erosion •

potential

avoid areas of actual and potential acid sulfate soils.•

Additional mitigation measures and standard controls to avoid

or reduce impacts are presented in Section 10.5.


OLYMPICDAM

See inset 2

See inset 1

Areas of potentialdisturbance to

inland ASS

LakeWindabout

PointLowlyWhyalla

Pimba

Woomera

Andamooka

Roxby Downs

Port Augusta

LakeMacFarlane

Lake Dutton

IslandLagoon

Lake Torrens

UpperSpencer Gulf

BH7BH6

BH5

BH4

BH3BH2

BH1

BH17

BH16

kp80

kp60

kp40

kp20

kp320

kp300

kp280

kp260

kp240

kp220

kp200

kp180

kp160

kp140

kp120

kp100

ASS sample locations






Rail alignment

Access corridor



EIS Study Area

Coastal Acid Sulfate Soil risk (CSIRO)

Low

Moderate

High

BH14

BH15

BH13BH12

BH9

BH8

BH10

KP10

0 5 10 15 20 25km

Inset 2Point Lowly

Investigation AreaInset 1

Port AugustaInvestigation Area

Moomba

Whyalla

Adelaide

Port Pirie

Roxby

Augusta

Downs

Port

Figure 10.7 Coastal acid sulfate soils (ASS), risk mapping and areas of potential disturbance to inland ASS

Olym

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ental Impact Statem

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10

OLYMPICDAM

Lyndhurst

Leigh Creek

Marree

Finniss Springs

Murnpeowie

Lake Eyre North

Lake Torrens

Lake Frome

Lake Eyre South

Lake Blanche

LakeGregory

Moomba

Andamooka

Roxby Downs

kp80

kp60

kp40

kp20

kp440

kp420

kp400

kp380

kp360

kp340

kp320

kp300

kp280

kp260kp240kp220

kp560

kp540

kp520

kp500

kp480

kp460

kp440

kp420

kp400

kp380kp360

kp340

kp320

kp300

kp280kp260

kp240kp220kp200

kp180

kp160

kp140

kp120

kp100

Lake CallabonnaFossil Reserve

Lake PalankarinnaFossil Reserve

Moomba

Whyalla

Adelaide

Port Pirie

Roxby Downs

Port Augusta

0 10 20 30 40 50km



Fossil Reserve

Eyre Formation

Bulldog Shale



EIS Study Area

Figure 10.8 Geological units known to contain fossils along the gas pipeline corridor options


10.5 impacT aSSeSSmenT and managemenT

10.5.1 Soil eroSion

Soil erosion may occur during and after rainfall or high winds.

The risk of erosion is increased if disturbance to the ground

surface breaks the crust or removes surface gravels or

vegetation. The degree of soil erosion depends on the

susceptibility of the disturbed soil type to various wind

velocities and rainfall volumes and intensities, as well as

landscape features such as slope and vegetation coverage.

The susceptibility of the various soil types to erosion was

described in Table 10.5 and illustrated in Figures 10.5 and 10.6.

On a linear basis, around 126 km of the northern route for the

gas pipeline corridor options has a high to very high erosion

potential, 180 km has a medium potential and 137 km has a low

potential. For the southern route option, around 47 km has a

high to very high erosion potential, 161 km has a medium

potential and 150 km has a low potential (see Figure 10.5). For

the southern infrastructure corridor, around 5 km has a very

high erosion potential, 49 km has a high potential, 170 km has

a medium potential and 175 km has a low potential (see

Figure 10.6).

Given the relatively flat terrain and the small, contained

catchments for most of the EIS Study Area (see Chapter 11,

Surface Water, for details), standard engineering practices

would control erosion in those areas with low and moderate

erosion potential. Such practices include minimising the area of

disturbance and stockpiling topsoil and cleared vegetation for

subsequent re-spreading over disturbed areas.

Additional erosion control measures would be implemented in

those areas with soils of high and very high erosion potential,

and at the site of the landing facility, desalination plant, Port of

Darwin facilities and associated infrastructure (as sediment

generated from these areas may enter ecologically sensitive

marine waters). These additional control measures are:

Erosion and sediment control plans (ESCP) that would:•

be developed in consultation with a marine ecologist −

with knowledge of the relevant receiving environment

(i.e. Upper Spencer Gulf, Darwin Harbour) so that

potential impacts on ecologically sensitive places are

avoided or minimised

include marked-up design drawings that show the −

location, extent and type of erosion control measures

proposed (e.g. silt fencing for terrestrial areas, silt

curtains for marine areas, catch banks or drains and rock

armouring for areas of potentially concentrated

stormwater flow).

An ESCP for areas of high to very high erosion risk along the •

gas pipeline corridor options. The plan would specifically

address:

dunefield areas, particularly those associated with the −

Strzelecki, Collina and Hope land systems (see Figure

10.3), as the susceptibility of these areas to erosion is

increased by the prevailing direction of the longitudinal

dunes (i.e. north-north-west to south-south-east) in

relation to the direction of pipeline construction, which

would necessitate traversing the dunes in an east to

north-east direction

undulating downs and rolling hills within the Mumpie soil −

unit where removal of the protective gibber surface

would increase susceptibility to water erosion due to the

dispersive subsoils and steep terrain

the bed, banks and overflow channel areas of the main −

watercourses, where flood flows with a significant

velocity may cause or increase stream bank and stream

bed erosion. Many soils associated with the stream

channels are dispersive cracking clay soils that are

particularly susceptible to erosion and most channels

currently exhibit significant erosion due to high cattle

stocking pressures.

Suitable erosion protection measures (e.g. silt fencing) •

would be installed on the downstream side of the

disturbance areas for the transmission line towers where

soils of high erosion risk have been identified (see

Figure 10.6) and in areas within 50 m of a drainage channel

or watercourse.

Erosion protection measures would be implemented to limit •

the disturbance to protective gibber surfaces (such as those

within the Arcoona land system between Woomera and

Roxby Downs) and salt crusts (e.g. at Lake Windabout

and Pernatty Lagoon). Where possible, ancillary

infrastructure (such as borrow pits, access tracks and

laydown yards) would be located outside these areas. Site

clean-up in these areas would also avoid grading or shallow

ripping of traffic compacted areas to retain the integrity of

the compacted surface.

Monitoring programs would be developed to ensure erosion and

sediment control measures were inspected, and maintained if

required, following each potentially erosive rainfall event (this

would be determined during the Environmental Management

Program (EM Program) and ESCP preparation). The monitoring

programs would be implemented during the construction phase

and continue during post-construction until the disturbed areas

were stabilised.

With the successful implementation of these control measures,

the residual impact to the environment from erosion and the

resulting sedimentation is considered to be low.

All excavation works for the existing operation are required to

be undertaken under the existing internal permit system. While

the excavation permit system includes inspection of sites for

potential heritage and native vegetation clearances, it also

outlines procedures required for reinstatement and

rehabilitation of excavations to promote regeneration of native

vegetation and to limit the potential for soil erosion. The

existing excavation permit system is considered appropriate for

the expanded operation.


10

As discussed above, additional control measures would be

implemented in areas with soils of high and very high erosion

potential and where construction occurs adjacent to marine

environments. Monitoring programs would be developed to

ensure erosion and sediment control measures were inspected

and maintained following each potentially erosive rainfall

event (this would be determined during the EM Program and

ESCP preparation).

10.5.2 acid SulFaTe SoilS

The desktop and field investigations established that some soils

within the EIS Study Area appeared to have the potential to

generate acid if disturbed (i.e. exposed to oxygen). The

comparison of laboratory results for these samples with

the action level criteria for ASS (see Table 10.2) is shown in

Table 10.6.

The data in Table 10.6 show that total actual acidity is well

below action level criteria for all sample locations. It does,

however, show that some locations have the potential to

generate acid if disturbed (as shown by the oxidisable sulphur

data), in which case soils in these areas would need to be

treated. The areas of potential disturbance to ASS include the

inlet to Lake Windabout (site BH05), Yorkey’s Crossing near Port

Augusta (site BH08), small areas adjacent to Port Bonython

Road (sites BH12 and BH13) and the proposed landing facility

sites (BH16: see Figure 10.7). Note that elevated levels were

also identified at BH01 (near Andamooka Road), but the

proposed expansion would not disturb this site.

lake Windabout

This sample collected at Lake Windabout (BH05) contained

monosulphides in near-surface sediments. While monosulphides

are known to be highly reactive, they were only found in very

thin surficial horizons (to a depth of 0.05 m) and so the quantity

of acid produced on oxidation would be very small. Lakes such

as Lake Windabout also form a sink for surface water and

groundwater flows, so the potential for off-site impact is

negligible. Furthermore, the proposed level of disturbance at

Lake Windabout would be minimal: the transmission line towers

would generally avoid these areas or require fill rather than

excavation and the water supply pipeline would be elevated

across the inlet to Lake Windabout instead of being buried in an

excavated trench. Given these factors, the standard engineering

practice of minimising disturbance and the effectiveness of soil

handling and lime dosing, if required, management measures

would ensure the residual impact of ASS in this area is negligible.

yorkey’s crossing near port augusta

The proposed transmission line would traverse intertidal areas

at Yorkey’s Crossing. However, the transmission line towers are

likely to be located on elevated terrain, which is outside of ASS

prone areas. If towers were to be located below 5 m AHD in the

area near BH08, further ASS investigations would be conducted

and an ASS management plan would be prepared if the sample

analysis was found to exceed the applicable criteria. The plan, if

required, would include control measures for ASS, including

appropriate soil handling methods and lime dosing rates. The

residual impact for potential disturbance to ASS at Yorkey’s

Crossing is categorised as low.

Table 10.6 comparison of soil samples with action criteria1

Sample reference number (see Figure 10.7)

Texture range (mcdonald et al. 1990)

Total actual acidity (molh+/t)

oxidisable sulphur (%S)

criteria exceeded

<1,000 t disturbed >1,000 t disturbed

BH01: 0–0.5 Coarse <2 0.1 Yes (0.03) Yes (0.03)

BH02: 0–0.3 Fine <2 <0.02 No No

BH05: 0–0.05 Fine <2 0.19 Yes (0.1) Yes (0.03)

BH05: 0.05–0.3 Fine <2 <0.02 No No

BH06: 0.8–1.0 Medium <2 <0.02 No No

BH08: 0.45–0.7 Coarse <2 <0.02 No No

BH08: 1.0–1.3 Fine <2 0.03 No Yes (0.03)

BH09: 1.1–1.35 Fine <2 <0.02 No No

BH12: 1.7–2.0 Fine <2 0.06 No Yes (0.03)

BH12: 2.0–2.3 Coarse <2 0.11 Yes (0.03)

Yes (0.03)

BH13: 1.5–1.7 Coarse <2 0.02 No No

BH13: 1.7–2.0 Fine <2 0.03 No Yes (0.03)

BH14: 1.5–1.7 Coarse <2 0.014 No No

BH15: 0.7–0.9 Fine <2 <0.02 No No

BH15: 1.8–2.0 Coarse <2 <0.02 No No

BH16: 0.2–0.25 Medium <2 <0.02 No No

BH16: 0.35–0.4 Fine <2 0.19 Yes (0.1) Yes (0.03)

BH17: 0.2–0.25 Coarse <2 <0.02 No No

1 Numbers in bold indicate concentrations above or equal to the action criteria.


proposed landing facility

The areas located at and adjacent to the proposed landing

facility are below 5 m AHD and would be disturbed during

construction. Shallow subsurface soils (0.35–0.4 m) exceeded

the applicable action level criteria but have a low acid

producing potential. Nevertheless, more extensive ASS

investigations would be undertaken at this site prior to

construction activities. Should these further investigations

detect oxidisable sulphur levels exceeding the applicable action

criteria, a site specific ASS management plan would be prepared.

The plan, if required, would include control measures for ASS,

including appropriate soil handling methods and lime dosing

rates. As management of ASS, once detected, is easily achieved,

the residual impact for disturbance is categorised as low.

Small areas adjacent to port Bonython road

The area adjacent to Port Bonython Road that may be disturbed

during pipeline construction has no, or very low, pyrite content

and has a low acid producing potential. As the action level

criteria were exceeded, and given the sensitivity of the

receiving environment, further ASS investigations would occur

once the final pipeline alignment had been determined and an

ASS management plan would be prepared before excavation

works commenced in this area. Given the practical ease and

effectiveness of ASS control measures, the residual impact for

potential disturbance to ASS near Point Lowly is categorised

as low.

port of darwin

The construction of facilities at the Port of Darwin would

generally be on reclaimed land and therefore would not disturb

acid sulfate soils. However, trenching below 5 m AHD may be

required to install service infrastructure. Prior to such ground

disturbance in these areas, testing would be undertaken for

potential and actual ASS. An ASS management plan would be

implemented for areas that exceeded action criteria as listed in

Table 10.2 or other relevant Northern Territory guidelines.

Given the minimal trenching required, the planned ASS testing

in risk areas and the implementation of an ASS management

plan where required, the residual impact for potential

disturbance to ASS at the Port of Darwin is categorised as low.

10.5.3 collapSing and SWelling SoilS

Collapsing soils are present in some areas of the EIS Study Area,

particularly the sand dunes near Port Augusta (kp 75; see

Figure 10.4). The trench proposed to be excavated through

these soils for the water supply pipeline has the potential to

become unstable and collapse. This may impact construction

personnel should they enter the trench in these locations.

Standard engineering practices such as shoring or similar

measures that retain the trench’s structural stability would be

used in these areas.

Expansive, cracking clays occur in several sections of the EIS

Study Area (see Table 10.4 and Figure 10.4). Significant shrink-

swell movements could damage the water supply pipe.

Appropriate bedding and backfilling of the pipe is standard

engineering practice in such soil types and would be used to

avoid potential impacts associated with the expanding and

swelling of cracking clays.

The rail line would cross the undulating sand dunes, swales and

clay pans of the Roxby land system and the highly expansive

clays of the Arcoona land system (see Figure 10.4). Pooling of

surface water following prolonged or major rainfall events,

though uncommon, could potentially cause slumping in parts of

the rail line as these clays softened. The problem is easily

managed by using culverts or other drainage features at

topographic low points. This has been considered during the

concept design phase (as is evidenced through the inclusion of

up to 140 culvert structures for the rail line), and would

continue to be investigated during the detailed design phase.

The residual impact associated with swelling and collapsing

soils is negligible.

10.5.4 Soil conTaminaTion

mine area

Elevated concentrations of metals and other potential

contaminants (including radionuclides) present in stormwater

run-off from on-site facilities such as the metallurgical plant,

hardstand areas and the RSF may lead to localised soil

contamination. Haul roads and bunds would be used to

intercept and convey stormwater run-off from these facilities to

naturally low lying areas within the landscape. Stormwater run-

off would be contained within the SML, and run-off potentially

containing radionuclides would be contained within a defined

area (see Chapter 11, Surface Water, for further detail). Post

closure, potentially contaminated soils would be assessed and

remediated as required (see Chapter 23, Rehabilitation and

Closure, for further detail).

As potential contaminants present in stormwater run-off would

be controlled and not go off-site, and identified contaminated

soils would be remediated post closure, the residual impact is

categorised as low.

port of darwin

The concentrate storage and loading facilities at the Port of

Darwin would be managed in a closed system including

negative pressure and automatic doors for the storage shed

and dedicated enclosed conveyors. Rail wagons would be

sealed with suitable covers to ensure containment of the load

during transport. Uranium oxide would be transported in sealed

drums within sealed shipping containers. Therefore, the

likelihood of contamination leading to environmental harm is

low and the residual impact of soil contamination from the

storage and transport of uranium oxide and concentrate is

categorised as negligible.


10

existing contaminated soils

No register is present in South Australia to identify areas of

known contaminated soils. However, contaminated soils may be

associated with industrial areas such as around Port Augusta

and Point Lowly. Strategies to identify and manage existing

contaminated soils prior to construction of off-site facilities

would be included in the EM Programs.

The Darwin Port Corporation consider the material used at the

East Arm for land reclamation to be ‘clean fill’ (GHD 2006).

Therefore, it is unlikely that contaminated soils would be

encountered during construction of the facilities.

chemical storage and accidental spills

Details of chemical storage and use are presented in Chapter 5,

Description of the Proposed Expansion. As some of the Olympic

Dam material is radioactive, spillages of all process materials

and products are treated seriously by BHP Billiton and systems

and procedures are in place to ensure that spills are identified,

reported, cleaned up and investigated to prevent recurrence.

Operational procedures at Olympic Dam require all spills (or loss

of containment spills) to be reported internally as environmental

incidents. At Olympic Dam the frequency, duration and severity

of all spillages are currently monitored including information on

the quantity of material and type of material.

A process to notify external agencies if the spill triggers the

external reporting level is also in place. Reporting criteria are

based on volume of spillage and whether the spill has occurred

inside or outside a bund which has been designed for the

purpose of containing a spill.

As part of contingency management, all parts of the existing

plant have undergone hazard and operability (HAZOP) reviews

to identify the potential for spills and the likelihood of spillages.

These reviews would occur for new plant or facilities, including

facilities at the Port of Darwin, installed as part of the

expansion project. Controls include bunding requirements and

access and egress for cleanup. Those areas which require

specific legislative requirements for spillage prevention, control

and management would also be addressed further in the

detailed design stage.

In the event of a spillage, there are a number of controls

available for operational personnel to contain spills including

temporary bunds and spill kits for spillage response and

operational and emergency response personnel are trained in

their use.

Fuel storages and other hazardous materials would be

appropriately bunded as required by South Australian, Northern

Territory and Australian statutes. The residual impact of soil

contamination associated with storage of fuels and other

chemicals is categorised as low. Risks as a result of accidental

spills and other unplanned events are addressed in Chapter 26,

Hazard and Risk.

10.5.5 FoSSilS

There are no areas containing registered fossils of significance

within the EIS Study Area, although an official fossil reserve

is located close to the gas pipeline corridor options

(see Figure 10.8). The geological units within the EIS Study Area

that potentially support fossils (Bulldog Shale and Eyre

Formation) are generally found at greater depths than would be

exposed by excavation during construction, which limits the

chance of disturbance. However, these geological units do occur

within the surface geology in some parts of the EIS Study Area

(see Figures 10.8 and 10.9), such as:

Bulldog Shale – occurs in surface geology within and around •

the SML, along the southern portion of the gas pipeline

corridor options, approximately 10 km south of Roxby Downs

township and the local Woomera area.

Eyre Formation – occurs within the surface geology of the •

gas pipeline corridor options and approximately 30 km south

of the Roxby Downs township.

As leaf fossils within the Bulldog Shale and plant fossils within

the Eyre Formation are relatively common and are not

considered to be significant by the South Australian Government,

no action would be taken should such fossils be discovered.

Fossil bones within the Bulldog Shale are considered to be

noteworthy. A procedure for identifying and treating such

fossils, should they be found during ground disturbance works,

would be included in the EM Program for the project

components requiring excavation in the Bulldog Shale areas as

shown in Figure 10.9 (see Chapter 24, Environment

Management Framework, for details of management plans). The

procedure may, for example, require the fossils to be

photographed and an appropriate person contacted at the

South Australian Museum to determine their significance and

any further mitigation measures that may be required. Given

the low likelihood of encountering significant fossils and the

measures that would be adopted in the event of a discovery,

the residual impact on fossils is categorised as negligible.

10.6 FindingS and concluSionS

Soil erosion

Soils within those areas proposed to be disturbed for the

expansion project have a susceptibility to erosion, once

disturbed, which varies from low to very high. However, the

degree of disturbance, the generally flat terrain and the small

catchment areas suggest that erosion categorised as low or

moderate can be readily managed. Additional erosion control

measures have been identified for those areas where the soil

erosion potential has been categorised as high and very high.

Implementation of management controls results in the residual

impact to the environment caused by erosion and subsequent

sediment deposition to be categorised as low.


LakeWindabout

PernattyLagoon

LakeMacFarlane

IslandLagoon

LakeDutton

OLYMPIC DAM

Andamooka

Roxby Downs

Woomera

Pimba

kp320

kp300

kp280

kp260

kp240

kp220

kp200

kp180

kp160

kp140

Moomba

Whyalla

Adelaide

Port Pirie

Downs

Port Augusta




Transmission line alignment

Rail alignment

Eyre Formation

Bulldog Shale



EIS Study Area0 5 10 15 20 25

km

Roxby

Figure 10.9 Geological units known to contain fossils along the southern infrastructure corridor


10

acid sulfate soils

Areas of potential disturbance to acid sulfate soils (ASS) include

several salt lakes, Yorkey’s Crossing near Port Augusta, and

small areas of coastal ASS adjacent to the proposed landing

facility and Port Bonython Road. The residual impact of

potential acid generation is low as areas that support potential

ASS are generally avoided or have low potential to generate

acid if disturbed. Where this is not the case (e.g. at the inlet

to Lake Windabout and the proposed landing facility),

additional ASS assessments would be undertaken and an ASS

Management Plan detailing required soil handling methods

and lime dosing rates would be developed prior to disturbance.

As management of ASS can be readily achieved, the residual

impact of disturbance in these area is also categorised as

negligible to low.

collapsing and swelling soils

Some areas supporting collapsing and swelling soils were

identified and mapped within the EIS Study Area. As standard

engineering practices can be readily implemented to ensure

protection of personnel and infrastructure assets, the residual

impact is negligible.

Soil contamination

Transport, handling and storage of fuel and other hazardous

materials within the SML, and at construction sites for

the associated infrastructure, will be in accordance with the

relevant State and Australian statutory requirements.

The objectives are to prevent spills from occurring and, if they

do, to contain the spillage to the immediate vicinity. Current

spill management and reporting procedures would continue for

the expanded operation. The potential for accidental spills

resulting in significant soil contamination is low.

Fossils

As the likelihood of encountering significant fossils within the

EIS Study Area is low, and contingency measures have been

identified in the event of a discovery, the residual impact is

categorised as negligible.

Topography and SoilS 1010 - BHP...proposed expansion are discussed in Chapter 12, Groundwater,...

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